BND, AGG, and TLT are three of the most commonly held US bond ETFs, and they represent genuinely different exposures within the bond market - not interchangeable “bond fund” options that can be swapped for each other without consequence. For a non-US investor specifically, there’s also a real, meaningful tax advantage worth understanding in detail: most of the interest income these funds distribute arrives with little to no US withholding, a genuinely different picture from equity dividend income covered throughout the rest of this site.
What Each Fund Actually Holds
BND (Vanguard Total Bond Market ETF) tracks a broad US investment-grade bond index - a diversified mix of US Treasuries, government agency bonds, and investment-grade corporate bonds spanning a range of maturities from short to long, designed to represent the broad US investment-grade bond market in a single fund.
AGG (iShares Core US Aggregate Bond ETF) tracks a very similar broad investment-grade index to BND, with a comparable holdings profile, comparable average duration, and comparable credit quality distribution - the two are close substitutes for each other, differentiated mainly by provider and minor index methodology differences rather than any meaningful difference in what an investor actually gets.
TLT (iShares 20+ Year Treasury Bond ETF) is meaningfully different from the other two in both composition and behavior - it holds exclusively long-duration US Treasury bonds with maturities of 20 years or more, making it far more sensitive to interest rate changes than BND or AGG’s more diversified, shorter-average-duration holdings, and carrying no corporate credit exposure at all (100% US government-backed).
Why TLT Behaves So Differently: The Duration Mechanic
Duration measures a bond fund’s sensitivity to interest rate changes - roughly, the approximate percentage change in a bond’s price for each one-percentage-point change in interest rates. Long-duration bonds like the ones TLT holds carry a duration figure meaningfully higher than the broader, shorter-average-duration mix in BND or AGG, meaning TLT’s price can move substantially more, in either direction, in response to the same interest rate shift.
A concrete illustration of the mechanic: if a fund carries an approximate duration of 17 years (a figure in the range TLT has historically carried, though the exact figure moves with market conditions and the fund’s underlying holdings), a 1 percentage point rise in long-term interest rates would be expected to produce an approximate 17% decline in the fund’s price, all else equal - and the reverse, a 1 percentage point rate decline, would be expected to produce an approximate 17% gain. BND and AGG’s shorter, more diversified duration profile - carrying an approximate duration roughly a third to a half of TLT’s - produces meaningfully smaller price swings for the same rate movement.
This makes TLT a genuinely different tool: less a “safe bond allocation” in the way BND or AGG might be used, and more a specific instrument for expressing a view on long-term interest rates, or for a targeted hedging role against certain other portfolio risks (long-duration Treasuries have, at various points, shown a tendency to rally during equity market stress, though this relationship isn’t guaranteed to hold in every downturn). Treating TLT as interchangeable with a genuinely conservative bond holding is a common and consequential mistake - it’s a bond fund, but not a low-volatility one.
The Tax Advantage: Portfolio Interest and Interest-Related Dividends
This is where bond ETFs offer a genuinely different tax picture than equity funds for a non-US investor. As covered in detail in our municipal bonds guide and main dividend withholding guide, interest income - including interest passed through by a US bond fund as an “interest-related dividend” under IRC §871(k)(1) - is generally exempt from the standard 30%-or-treaty-rate withholding that applies to equity dividends, when the underlying interest itself would qualify for the portfolio interest exemption under §871(h).
In practice: a substantial portion of the distributions from BND, AGG, and TLT - funds holding US Treasuries and other qualifying debt instruments - can arrive with little to no US withholding, assuming the fund properly designates the distribution as interest-related and your broker applies the exemption correctly at the point of payment. This is a meaningfully more favorable withholding picture than equity dividends face from the same broker, and it’s worth checking your Form 1042-S against, since brokers do not always apply this exemption correctly, as flagged in our main withholding guide - a mistaken 30% withholding on what should have been a largely exempt interest distribution is a common, recoverable error, not something to simply accept.
Why this exemption exists at all: the portfolio interest exemption was created, in broad terms, to keep US debt markets attractive to foreign capital by not taxing foreign holders of US debt instruments the way foreign holders of US equity are taxed - a policy choice with a real, practical benefit for non-US bond ETF holders specifically, distinct from the equity-dividend withholding regime covered throughout the rest of this site’s tax content.
Credit Risk: A Dimension Worth Separating from Duration Risk
BND and AGG include investment-grade corporate bonds alongside government and agency debt, meaning a portion of their holdings carry genuine credit risk - the risk that a specific corporate issuer defaults or is downgraded - layered on top of interest rate risk. This is a different risk than TLT’s, which holds exclusively US Treasury debt and therefore carries essentially no credit risk (Treasury debt is generally treated as the risk-free benchmark within US fixed income markets), only interest rate risk.
The practical implication: BND and AGG’s diversification across Treasury, agency, and corporate debt spreads risk across more sources but introduces a risk type TLT doesn’t carry, while TLT’s exclusively-Treasury holdings concentrate risk entirely into interest rate sensitivity, with no credit-risk diversification benefit to offset it. Neither structure is inherently better - they’re simply different risk compositions serving different portfolio roles.
Choosing Between Them
BND or AGG suit an investor wanting a straightforward, diversified fixed-income allocation as a stabilizing portfolio component - similar in purpose to the conservative leg described in our barbell portfolio guide, though that guide specifically recommends shorter-duration Treasuries for genuine stability during a market downturn, a role BND/AGG’s more moderate duration profile fits reasonably but not as precisely as a dedicated short-duration Treasury fund would, given their inclusion of longer-duration and corporate holdings within the broad index.
TLT suits an investor with a specific view on long-term interest rates, or seeking a more targeted long-duration Treasury exposure for a specific portfolio role - not a default “safe” bond allocation given its meaningfully higher price volatility relative to BND or AGG. An investor reaching for TLT expecting BND-like stability is likely to be surprised by how much TLT’s price can move in either direction.
For an investor specifically prioritizing capital stability over yield or a rate view, a fund with a shorter average duration than any of these three - not covered in this specific comparison, but worth researching separately - may better serve that narrower goal than BND, AGG, or TLT, all of which carry meaningfully longer average duration than a genuinely short-term Treasury fund.
Frequently Asked Questions
Do BND, AGG, and TLT pay dividends the same way an equity ETF does, or is the mechanic different? The distribution mechanic is broadly similar in form (a periodic cash payment to shareholders), but the underlying source is interest income from the fund’s bond holdings rather than dividend income from equity holdings, which is exactly what makes the §871(k)(1) interest-related dividend exemption relevant to these three funds specifically and not to a fund like VOO or VTI.
Can the interest-related dividend exemption fail to apply even on a Treasury-heavy fund? Yes - the exemption depends on the fund properly designating the relevant portion of each distribution as interest-related, and on your broker correctly applying the exemption at the point of withholding. A fund’s Treasury-heavy composition doesn’t automatically guarantee correct withholding treatment on your specific statement; verification against your Form 1042-S remains necessary.
Is TLT ever a reasonable choice for a genuinely conservative, risk-averse investor? Generally no, given its price volatility - a risk-averse investor is usually better served by BND, AGG, or a shorter-duration Treasury fund. TLT tends to suit investors with a specific, active view or role for the position, not investors seeking straightforward capital preservation.
How does rising versus falling interest rates affect the choice between these three funds? An investor expecting rates to fall meaningfully would see TLT benefit more than BND or AGG, given its longer duration - and the reverse holds if rates are expected to rise. This is inherently a forecasting-dependent consideration, and this site generally treats interest rate forecasting with the same skepticism it applies to market-timing and currency-timing elsewhere.
A Working List for Bond ETFs for International Investors
- Understand that BND and AGG are close substitutes for broad, diversified bond exposure, while TLT is a meaningfully different, more volatile, long-duration-specific instrument
- Check your Form 1042-S to confirm interest-related distributions from these funds are receiving the reduced or zero withholding they’re generally entitled to under IRC §871(k)(1) - and pursue a refund via Form 1040-NR if withholding was applied incorrectly
- If seeking genuine stability for a barbell or defensive portfolio role, confirm the specific duration profile matches your goal - TLT’s long duration works against a pure stability objective
- Recognize that BND and AGG carry corporate credit risk that TLT’s exclusively-Treasury holdings don’t share, while TLT concentrates entirely into interest rate risk
- Confirm PRIIPs/UCITS considerations apply if you’re an EU or UK investor, the same as with any other US-domiciled fund
The Practical Upshot of Bond ETFs for International Investors
BND, AGG, and TLT are not interchangeable “bond ETF” options - BND and AGG offer diversified, moderate-duration exposure with some corporate credit risk, while TLT is a distinctly more volatile, long-duration, credit-risk-free instrument suited to a specific rate view or portfolio role rather than default stability. For a non-US investor, all three offer a genuinely favorable tax feature equity funds don’t share: much of their interest income can arrive with little to no US withholding under the portfolio interest exemption, worth confirming on your actual dividend statements rather than assuming it’s been applied correctly.
General information about Bond ETFs for International Investors - not a recommendation you should act on unaided. Duration figures cited are illustrative and change with market conditions and fund composition - confirm current details directly with the fund provider and your broker.
Sources: iShares 20+ Year Treasury Bond ETF (TLT) product page - effective duration has run in the 16.5-17.5 year range, most recently around 16.8 years. Duration changes as the underlying holdings roll; verify the current figure on the fund page.
Related Guides
- Municipal Bonds and Foreign Investors: Tax Treatment
- US Dividend Withholding Tax for Foreign Investors
- Building a Barbell Portfolio: TQQQ Core Plus Bond Ballast
